Vacuum operated compound double-acting piston pump or compressor



G. c. GRAHAM 3,544,239 VACUUM OPERATED COMPGUND DOUBLE-ACTING PISTONPUMP OR COMPRESSOR Dec. 1, 1970 4 Shee cs-Sheet 1 Filed NOV. 25, 19681W7); M6437} I ,-1970 v e. c. GRAHAM 3,

VACUUM OPERATED COMPOUND DOUBLE-ACTING PISTON PUMP- OR COMPRESSOR FiledNov. 25, 1968 4 Sheets-Sheet 5 lb? M M2 INVENTOR /53 kaflqs C GPA/MM BYI Dec. 1, 1970 c, GRAHAM 3,544,239

VACUUM OPERATED COMPOUND DOUBLE-ACTING PISTON PUMP OR COMPRESSOR FiledNov. 25, 1968 4 Sheets-Sheet 4 T135. TIL-11B.

INVENTOR BY z ATTOEZEY United States Patent 3,544,239 VACUUM OPERATEDCOMPOUND DOUBLE- ACTING PISTON PUMP 0R COMPRESSOR George C. Graham, 76Crest Road, Ridgewood, NJ. 07450 Filed Nov. 25, 1968, Ser. No. 778,614Int. Cl. F04b 35/00; F011 23/00 US. Cl. 417-403 34 Claims ABSTRACT OFTHE DISCLOSURE A vacuum operated pump having an axially aligned pair ofpistons of different diameters operating in respective low and highpressure cylinders where a piston operating in the larger cylindercompresses air and transmits said compressed air into the smaller highpressure cylinder where the smaller piston produces further and highercompression for transmission to work apparatus or storage means. Theinvention further includes a control rod operating in conjunction withthe vacuum diaphragm and mounted axially in respect of said diaphragmand said pistons and extending externally of the apparatus housing tooperate an alternating vacuum control mechanism.

BACKGROUND OF THE INVENTION Field of the invention Description of theprior art The present invention constitutes an improvement over priorart devices such as disclosed in the following US. Pats. Nos. 2,136,475,2,630,102, 3,148,825, 3,151,804, 3,151,805, 3,253,775 and 3,339,830. Theprior art devices as exemplified by said patents manifest variousfunctional deficiencies inherent in their respective structures. Oneserious drawback is involved in the mounting of a control elementlaterally of the reciprocating piston elements for operating analternating vacuum control mechanism thereby subjecting the workingparts of the apparatus to off center stresses that derogates from thedesired balance that reciprocating parts should exhibit in performingtheir pumping functions.

In some prior art devices, the lateral control element must, ofnecessity, extend through a piston wall or through a wall of a vacuumchamber thereby involving leakage of air which considerably reduces theefliciency of the pump. In efforts to counteract such unbalancingforces, prior art devices were constrained to incorporate extremelyclose tolerances between working parts which are deleterious to theoperating function and structure and involved complex means for reducingleakage of air either from the piston cylinders or from the vacuumchambers.

Also, in prior double-acting vacuum operated pumps, the pistons havebeen located on opposite sides of the vacuum operated diaphragm and havebeen located within respective vacuum chambers on opposite sides of thediaphragm. This reduces the eifective area of the diaphragm by the areaof the piston by as much as approximately 15% on the low pressure side,and approximately 10% on the high pressure side in one such prior artdevice. Likewise, the cubic content of each vacuum chamber is 3,544,239Patented Dec. 1, 1970 increased and thus requires more volume of vacuumper stroke as Well as higher vacuum to offset loss of diaphragmeffective area for a given output pressure. Since the movable pistonsare operative within the respective vacuum chambers and are movable inrespect thereof while nega tive pressures are being induced therein, itis manifest that considerable loss in pumping efliciency has beenexperienced in such prior art devices.

Summary of the invention In order to overcome the disadvantages anddeficiencies of prior art apparatus, the present invention comprises anovel arrangement of mounting two pistons longitudinally in respect ofeach other on the same operating axis in separate piston cylinders, bothof said cylinders being aligned axially on one side only of the vacuumoperated diaphragm of the pump. The two cylinders are eifectivelyisolated from the vacuum chambers within which the diaphragm isoperative whereby vacuum losses within said vacuum chambers arepractically eliminated.

One piston is operative in a large low pressure cylinder for compressingair during one half of the operating cycle of the pump and transmittingsaid compressed air to the second smaller high pressure cylinder wherethe second piston is operative on the second half operating cycle tocompress the air to a higher pressure for transmission to work orstorage apparatus.

Furthermore, an additional feature of the invention is the mounting of acontrol element axially of the vacuum diaphragm and axially of the twopistons, said control element extending externally of the apparatushousing and operating an alternating vacuum control mechanism.

By mounting the control element axially of the operating parts in theinterior of the apparatus, no off-center stresses are applied to saidoperating parts whereby pumping efliciency is not reduced.

The axial location of the control element in respect of the operatingparts and in respect of the apparatus housing obviates the necessity forcomplex and expensive sealing means to preserve the negative pressureconditions within the vacuum section of the apparatus and permits theuse of comparatively wide tolerances without any reduction in pumpingefliciency.

A further feature of the invention is the provision of a seal in thepartition between the vacuum chamber and pumping chamber of theapparatus, said seal being effective during both rectilinear motions ofa rod moving through an O-ring. The O-ring provides a vacuum seal forthe vacuum chamber when negative pressure is being induced thereinadjacent said partition, notwithstanding the opposing frictional forceof a rod moving through said O-ring during that time. Said O-ring alsoperforms its scaling function when the piston assembly mounted on saidrod moves toward said partition and produces increased air pressure forurging said O-ring into its sealing position.

These and other novel features and advantages of the present inventionwill be described and defined in the following specification and claims.

BRIEF DESCRIPTION OF THE DRAWINGS 0 a portion of the upper piston shownin FIG. 1A aftersaid piston has started its upward stroke;

. FIG. 1D is an enlarged fragmentary section .view of a portion of theupper piston shown in FIG. 1B after said piston has started its downwardstroke;

FIG. 1E is an enlarged fragmentary section viewof a portion of the lowerpiston shown in FIG. 1A after said piston has started its upward stroke;

. FIG. 1F is an enlarged fragmentary section view of a portion of thelower piston shown in FIG. 1B after said piston has started its downwardstroke;

FIG. 2 is a top fragmentary view of the device show in FIGS. 1A and 1B,some parts being shown in section, some parts in dotted outline, andsome parts partly broken away, and particularly illustrating the portionof the'vacuum-control valve mechanism and its operating linkages foralternating the vacuum conditions in the interiOr of the pump;

FIG. 3 is a fragmentary view similar to FIG. 2 showing the valvemechanism in an alternate position;

FIG. 4 is similar to FIG. 3 with further parts being broken away andother parts being shown;

FIG. 5 is an enlarged fragmentary perspective view of the mechanismshown in FIGS. 2, 3 and 4;

, FIG. 6 is a view taken on line 66 of FIG. 5;

- FIG. 7 is an enlarged perspective view of the top of the valveelement;

FIG. 8 is a perspective view of the bottom of the valve element shown inFIG. 7;

1 FIG. 9 is a fragmentary central section view of the apparatus shown inFIGS. 1A and 1B showing an alternative embodiment of the apparatus inone position;

FIG. 10 is similar to FIG. 9 showing parts of the apparatus in anotherposition;

FIG. 11 is similar to FIGS. 3 and 4 with further parts omitted andshowing the connection of a valve detent spring; and V I FIG. 12 is aperspective view of a valve detent spring.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1A and 1B of the drawingeach show respective complementary halves of the apparatus herein invertical section wherein like numbers refer to similar parts which areshown in different operational locations in said figures. Except for thealternating vacuum control and other parts specified herein, each partof the device may be assumed to be substantially circular in horizontalcross-section.

Referring now to the drawings in detail, the body of the devicecomprises a pair of hell sections 11 and 12, each having annular matingflanges 13 and 14, respectively, which are secured together by means ofa plurality of spaced apart screws 16 in circular array. Clamped fastbetween flanges 13 and 14 is the peripheral edge portion of a flexiblediaphragm 17 which is movable within the space enclosed by bell sections11 and 12 and which di-.

vides and separatessaid space into two chambers 18 and 19'which varyinversely in volume according as said diaphragm moves in one verticaldirection or the other. Bell section 11 has a top end wall 21 which hasa central axial aperture 22 which accommodates a reciprocating controlrod 23 therein. End wall 21 has a raised collar 24 surrounding rod 23and encloses a widened axial aperture in which is positioned O-rng 26which is held captive by a spider retaining ring 27 secured frictionallywithin collar 24. O-ring 26 serves as a one-way vacuum seal for chamber18.

a Bell section 12 has an' end wall 28 that serves as a partition betweenvacuum chamber 19 and the piston assembly of the apparatus. Partition 28has a central axial aperture 34 through which tubular shaft orpiston'rod section 36 moves reciprocably, there being a slight clearancebetween said rod and said aperture. Mounted on the upper and lowersurfaces of the central portion of diaphragm 17 are respective circularclamp plates 37 and 38, said clamp plates being secured t ge her y m anof threaded nut 43 mating with threaded .rod 36. The lower portion ofrod 23 extends freely longitudinally with wide clearance through axialaperture 44 in nut 43 and through axial aperture 46 in rod 36. Thevertical reciprocating motion of diaphragm 17 imparts a correspondingreciprocating motion to rod section 36.

Integrally formed on the lower surface of partition 28 of hell element12 is a collar 47 coaxially aligned with aperture 34. Formed withincollar 47 is an annular recess 48 which accommodates a somewhat looselyfitting O-ring 49 which serves as a seal between partition 28 androdsection 36. O-ring 49 is held captive within recess 48 by means of aspider retaining ring 51 whose inside diameter provides a wide clearancefor rod 36, thereby permitting free flow of air therethrough.

Formed integrally with and arrayed in a circle near the periphery ofwall 28 ofbell section 12 are a number of spaced apart bosses 56extending downwardly thereof, said bosses each having a longitudinalthreaded recess 57. A compound piston pressure chamber housing,generally designated 58, is formed of two integrally formed coaxialsections, namely, a low pressure cylinder 59 and a high pressurecylinder 61 whose diameter is smaller than that of cylinder 5-9.Cylinder 59 has a plurality of integrally formed spaced apart outwardlyextending bosses 62, each having an aperture through which a bolt 63extends to engage respective threaded recesses 57 in bosses 56. Theupper circular end of cylinder '59 has an annular recess accommodatingresilient O-ring '64 which is caused to bear against the bottom surfaceof wall 28 when bolts 63 are tightened thereby producing a leak-tightseal between said cylinder and said wall.

Threadedly or otherwise secured to rod section 36 is a cylindricalpiston 66 which is moved reciprocably by said rod section within lowpressure chamber 67 bounded by cylinder 59. The upper perimeter portionof piston 66 has an annular recess 68 which accommodates a resilientO-ring 69.'The top peripheral area of piston 66 has a plurality ofspaced apart apertures 72 in circular array which communicate withrecess 68 to provide for bypass of air during the downward suctionstroke of piston 66 (FIG. 1A). During the upward pressure stroke ofpiston 66, O-ring 69 is urged against flange 73 of rim 68 (FIG. 10) so,'that during its upward stroke, piston 66 compresses the air into theupper portion of chamber 67.

Piston 66 is provided with a plurality of spaced apart laterallyextending apertures 74 which provide for bypass of air from the bottomof chamber 67 through apertures 72 during the downward suction stroke ofpiston 66 when O-ring 69 is urged upwardly against flange 75 of saidpiston. Mounted in a suitable annular recess 76 in the lower peripheryof piston 66 is a lubricated or unlubricated felt or plastic ring 77which serves to ensure the alignment of piston 66' and toprevent scoringbetween parts. Recess 76 communicates with an optional auxiliary annularrecess 78 which serves as an expansion chamber for ring 77 and tocontain a lubricant, if desired or necessary, for said ring.

Threadedly or otherwise secured to the lower end portion of rod section36 is a second tubular rod section 81 which has an axial aperture 82which accommodates a longitudinally movable valve pin 83. Mounted faston the lower end of valve pin 83 is a valve 84 made of a suitable.

resilient material such as rubber, orthe like, and which cooperates witha recessed valve seat 86 formed in the lower end of second piston rod81. Valve 84 is normally urged against valve seat 86 by the action ofspring 87, the lower end of which bears against an interior annularshoulder formed in rod 81, the upper end of which bears against a collar88 mounted fast at or near the upper end of valve pin 83.

Threadedly secured or otherwise mounted fast at the lower end portion ofrod 81 is a high pressure piston 91 which moves reciprocably within highpressure chamber 92 of cylinder 61. Piston 91 has a peripheral annularrecess 93 which accommodates an O-ring 94 made of suitable resilientmaterial.

In some embodiments, the inner portion of recess 93 comprises agenerally V-shaped annulus formed by walls 96 and 97 arrayed at anincluded angle on the order of about 75 to 90. Walls 96 and 97 terminatein walls 98 and 99, each of which are arrayed directly perpendicularlyto the axis of the pump or are inclined, respectively, upwardly anddownwardly from the perpendicular by an angle of from to about O-ring 94is nested in recess 93 with only a minimum amount of pressure againstwalls 96 and 97 and the interior wall of chamber 92 so that there is aminimum of deformation or peripheral squeeze of said O-ring when piston91 is at rest.

By arranging for the recess 93 to have the special configuration formedby walls 96, 97, 98 and 99, there is ample space around O-ring 94 topermit its normal expansion due to heat created by the compression ofair in chamber 92. In FIGS. 1A and 1B, O-ring 94 is shown in a neutralposition at the respective ends of the downward and upward strokes ofpiston 91. The operating action of O-ring 94 will be explainedhereinafter as particularly shown in FIGS. 1E and IF.

Mounted in an annular recess 100 in the perimeter of piston 91 is alubricated or unlubricated felt or plastic ring 101 which ensures thelongitudinal alignment of piston 91 as well as prevents scoring betweenparts. Recess 100 communicates with an optional auxiliary annular recess102 which serves as an expansion chamber for ring 101 and to contain alubricant, if desired or necessary, for said ring.

Formed integrally between cylinders 59 and 61 is an annular shoulder 103through which is bored a plurality of spaced apart ports .104 whichprovides for communication of atmospheric air with chamber 92 ofcylinder 61 above piston 91 and with chamber 67 below piston 66.Integrally formed at the lower end of cylinder 59 is a downwardlyextending flange 105 which forms an annular compartment with cylinder 61to accommodate a filter ring 106 which is retained in place by aperforated ring '107 secured between flange 105 and the exterior surfaceof cylinder 61. Filter 107 serves to prevent contamination ofatmospheric air introduced into pumping chambers 67 and 92 by dust orother foreign particles and materials.

Located centrally in end wall 108 of cylinder 61 is an outlet port 109which communicates with a valve housing 111 formed integrally with andextending downwardly from said end wall. Positioned in the interior ofhousing 111 is a check valve 112 made of a suitable resilient materialor the like, that is normally urged against valve seat 113 by one end ofvalve spring 114, the other end of which bears against tubular plug 116threadedly inserted into the end of valve housing 111. Plug 116 has anintegrally formed nut 117 by which said plug is threadedly removed andinserted. Integrally formed with nut 117 is a tubular ridged extension118 to which suitable flexible connecting tubing is attached fortransmitting air under pressure from cylinder 61.

A short distance above the top of piston 66, piston rod section 36 has alateral port 121 which permits communication between that portion of lowpressure chamber 67 above piston 66 and longitudinal aperture 82 inpiston rod section 81 whereby during the upward stroke of piston 66valve 84 is caused to become spaced apart from its valve seat (FIG. 1B)against the action of spring 87 so that air being compressed by theupward stroke of piston 66 is caused to enter into chamber 92 during theupward movement of piston 91. Thereafter, the downward motion of piston91 causes the further compression of the air in chamber 92 and theexpulsion of said air under pressure past valve 112 during which timevalve 84 is firmly urged against valve seat 86 to prevent escape of airupwardly into aperture 82.

Mounted at the lower end portion of control rod 23 is a ring 122.Control rod 23 moves longitudinally in respect of nut 43 and pistonsection 36. Upward motion is imparted to control rod 23 by interiorannular bottom 123 of rod section 36 against the lower end of controlrod 23 and the lower surface of ring 122, while downward motion isimparted to said control rod by the lower end of nut 43 bearing againstthe top surface of ring 122. It is evident that the longitudinal motionspan of control rod 23 is shorter than the motion span of piston section36 since piston section 36 performs a work function throughout both itscomplete upward and downward strokes whereas control rod 23 is requiredonly to perform a short work stroke to operate a flip-flop oralternating mechanism described hereinafter for controlling the vacuumconditions in chambers 18 and 19 of the apparatus.

Aperture 44 provides a wide clearance to compensate for any possiblemisalignment of control rod 23. Also, the diameter of aperture 46 islarge enough to provide a wide clearance for ring 122 for the samepurpose.

Integrally formed with or otherwise mounted on one side of bell section11 is a valve housing 131 which has an integrally formed, outwardlyextending coupling tube 132, to which suitable, flexible hose may beattached for connection to the manifold of an automotive engine or thelike which produces negative pressure. Tube 132 communicates with port133 formed in the top surface 134 of housing 131. Port 133 is flanked onboth sides by respective ports 136 and 137. Port 136 communicates by wayof channel 138 and through flanges 13 and 14 with chamber 19 in bellsection 12, while port 137 communicates by way of channel 139 in housing131 with chamber 18 in bell section 11. Other suitable means may bedevised for connecting ports 136 and 137 with respective chambers 18 and19.

Mounted pivotally around pin 141 on the top surface 134 of housing 131is valve element 142, as shown in FIGS. 2-8, the bottom surface of saidelement having an arcuate channel 143 as shown particularly in FIGS. 6and 8. Recess 143 cooperates with ports 133, 136 and 137, in such manneras to establish communication between central vacuum port 133 and eitherone only of ports 136 and 137 according as said valve element is movedpivotally into either of two opposite directions as shown in FIGS. 2 and3. When valve element 142 is pivoted clockwise as shown in FIG. 3,vacuum port 133 communicates through channel 143 with port 136 whereby anegative pressure is induced in chamber 19 of bell section 12 therebyproducing downward movement of diaphragm 17 along with the downwardmovement of all of the other piston rod and piston elements connectedthereto, see FIG. 1A. When valve element 142 is pivoted counterclockwiseinto the position shown in FIG. 3, vacuum port 133 communicates throughvalve channel 143 with port 137 whereby negative pressure is induced inchamber 18 in bell section 11, thereby producing the upward movement ofdiaphragm 17 as well as the upward movement of the piston rods andpistons connected thereto as shown in FIG. 1B.

A pair of spaced apart abutments 146 and 147 are secured by suitablepins in the top wall 134 of housing 131 and they serve to limit therespective clockwise and counterclockwise movements of valve element142. Abutments 146 and 147 may be made of a suitable resilient mate rialsuch as rubber or the like to absorb the impact of element 142.

Pivotal motion in clockwise and counterclockwise directions is impartedto valve element 142 by means of movements, retained against either oneof abutment 146 and 147 by means of a semi-circular detent spring 152,one end of which isattached to tail projection 153 on valve element 142,the other end ofwhich is connected to post 154 mounted on the top ofhell section 11. Spring 152 offers no appreciable resistance, however,to the oscillating movement of valve 142.

The hub of valve actuator 151 has a circular projection 155 extendingdownwardly to the top surface 134 of housing 131 and the pivot apertureof valve 142 surrounds said projection with a sliding fit and is movablepivotally relative thereto, see FIG. 6.

Valve actuator 151isalso maintained intermittently between clockwise andcounterclockwise motions by means of a link 156 having a forked endrecess 157, the inner end of which is always urged against pin :8mounted off-center on actuator 151. An elongated slot 159 at the otherend of link 156 is engaged by and moves laterally relative to a post 161mounted in the top wall 21 of bell section 11. A coil spring 162surrounding link 156, one end of which bears against post 161, the otherend of which bears against a shoulder 163 in said link,

serves to. maintain valve actuator 151 in a stationary positionintermittently between clockwise and counterclockwise motions of saidactuator. Slot 159 serves to permit the free pivoting action of link 156relative to pins 158 and 161 while continuing to be engaged thereby.

Clockwise and counterclockwise motion is imparted to valve actuator 151by means of a link bar 166 near one end of which is an elongated slot167 which is engaged by a pin 168 mounted off-center on the top of saidactuator. Slot 167 permits actuator 1-51 to move to opposite restpositions as determined by link 156 and spring 162, after link bar 166has caused said actuator to move past the dead center position betweenits successive clockwiseand counterclockwise movements. Spring 162 andlink 156 work in conjunction with link bar 166 to produce the desiredsnap action for valve 142.

The other end of link bar 166 is connected pivotally to the lower forkedportion of pivot bar 171 by means of pivot pin 172. The upper portion ofpivot bar 171 is mounted pivotally by means of pin 173 upon a post 174mounted fast in the top wall 21 of bell section 11. Pin 173 extendsthrough washers 176 on opposite sides of post 174 and through pivotblock 177. Both pivot bar 171 and pivot block 7177 are mounted fast uponpin 173 'whereby they both move pivotally in unison relative to post174.

Pivot block 177 has a pair of spaced apart arms 178, each of which areengaged by corresponding recesses 179 in the sides of actuator block 181mounted threadedly on the top of control rod 23. The top of control rod23 hasa slot 182which permits rotation thereof by means of a screwdriver or the like in order to adjust the requisite height of actuatorblock 181 relative to said rod. Threadedly mounted on the top of controlrod 23 is a nut 183 for locking actuator block 181 into the desiredlocation onsaid rod.

The reciprocating vertical motion of control rod 23 producescorresponding reciprocating motions on the part of pivot block 177,pivot bar 171, link bar 166, valve actuator 151, resulting in producingthe reciprocating clockwise and counterclockwise motion of valve element142 whereby negative pressure is induced alternately in chambers 18 and19.0f bell sections 11 and 12. It is to be noted that upon the action ofvalve element 142 to produce negative pressure in either one of chambers18 or 19, the other chamber is exposed to the atmosphere through itsrespective port 137 or 136-, while negative pressure is being appliedthrough port 133 from the automotive manifold, or the like.

In some embodiments where the vacuum control valve have any associatedspring elements for producing snap action and for maintaining thevalving element in its intermittent position between oscillations, it iscontemplated thatthe apparatus of the present invention may be modifiedas shown in FIGS. 9 and 10 by providing within the interior of pistonrod section 36 a helical, spiral spring 186, the larger end of whichrests upon the floor 123 of the interior of said piston rod sectionwhile the upper, smaller portion of said spring extends freely upwardlyinto the interior of said rod section. Also mounted in the interior ofpiston rod section 36 is a helical coil spring 189, the upper end coilof which bears against and is retained frictionally within a recessedshoulder of tubular nut 43, the other end of said spring extendingdownwardly freely into the interior of said piston rod section.

Ring 122. within the interior of piston rod section 36 is normallyspaced apart from either spring 189 or 186 when diaphragm 17 is at restmidway between bell sections 11 and 12. Ring 122 is capable of movingthrough approximately 60 to percent of the length of the central portionof the interior of rod section 36 without contact with either of saidsprings when the latter are in their natural released conditions.

When diaphragm 17 is ,caused by negative pressure induced in chamber 19to move downwardly, the lower end of spring 189 which is normally in therelaxed condition as shown in FIG. 10 impinges upon the top surface ofring 122 and becomes wholly or partially collapsed within the interiorof nut 43. Thereafter, upon continued downward movement of diaphragm 17and nut 43, ring 122 and control rod 23 also move downwardly until thepoint of dead center between alternate positions of the substitutedvacuum control valve is reached, at which time spring 189 expands andproduces an instantaneous overthrust force upon ring 122 to impel thelatter to move beyond said dead center condition whereby said vacuum.control valve is moved by rod 23 into a position which is alternate oropposite from the previous position of said valve.

Upon the change of position of the vacuum control valve, the pressureconditions on diaphragm 17 are changed in the opposite direction by theinduction of negative pressure in chamber 18 thereby causing thediaphragm to move upwardly, during which time piston rod section 36 alsomoves upwardly. During this upward movement, floor 123 causes the upperfree end of spring 186 to impinge upon the bottom surface of ring 122,whereby said spring 186 becomes collapsed between the bottom surface ofring 122 and floor 123. The continued upward movement of piston rodsection 36 and floor 123 causes the concomitant upward movement of ring122 and control rod 23. Here, again, when ring 122 reaches the locationwhere the substituted vacuum control valve is at dead center, spring 186expands and produces an instantaneous overthrust force upon ring 122 tourge the latter and control rod 23 beyond said dead center point wherebythe vacuum control valve is moved into a position which is alternate oroppositelfrom its previously held position in order to reverse thepressure conditions upon diaphragm 17.

The embodiment shown in FIGS. 9 and 10 is useful with an alternatingvacuum control mechanism that is mounted centrally on the top of bellsection 11 and substantially axial with control rod 23, where springs186 and 189 perform the corresponding overthrust function as performedby spring 162 in the embodiment shown in FIGS.

In both respective embodiments, spring 162 and springs 186 and 189provide a snap action thrust for moving the respective vacuum controlvalves into opposite valving positions intermittently betweenoscillations from one position to the other. While a detent function isperformed by spring 152 to maintain valve 142 in position betweenoscillations, other suitable detent means, known in the art, will beincluded in any substituted valve control element that would be mountedaxially with control rod 23 in the embodiment shown in FIGS. 9 and 10.

OPERATION In operation, the apparatus is intended to act as a pump forproducing air under pressure to supply .power for apparatus such aswindshield wipers, tire inflater mechanisms, shock absorbers, loadleveling devices, air brakes, window locks, window openers and closers,seat adjusters, air horns, and the like, for automobiles and for otherequipment such as air mattresses, water systems, paint, fertilizer andinsecticide sprayers, and the like.

Being a vacuum operated pump, the apparatus is connected by way ofcoupling tube 132 to the manifold of an automotive engine or to othersuitable sources of negative pressure. This negative pressure iscontrolled by way of an oscillating vacuum control valve to producealternating negative pressure in chambers 18 and 19 within bell sections11 and 12 containing a movable diaphragm 17 to which the pumping pistonsare operatively connected. When negative pressure is induced throughport 136 into chamber 19, said negative pressure causes diaphragm 17 tomove downwardly as shown in FIG 1A. This action is permitted by exposingchamber 18 to the atmosphere through port 137 as shown in FIG. 2.

Toward the end of the downward motion of diaphragm 17 as well as of thedownward motion of control rod 23, the linkages connected to the upperend of said control rod cause valve element 142 to move counterclockwiseinto the position shown in FIG. 3 where port 136, as well as chamber 19,are now exposed to the atmosphere and concurrently port 137 of chamber18 is now connected to exhaust port 133 whereby negative pressure startsto be induced within chamber 18.

Because of the changed pressure conditions existing on diaphragm 17, thenegative pressure in chamber 18 causes said diaphragm to move upwardlyas shown in FIG. 1B.

Toward the end of the upward stroke of control rod 23, the linkagesconnected to the upper end of said rod now cause valve element 142 tomove clockwise into the position shown in FIG. 2. By this action, port137 and chamber 18 are now exposed to the atmosphere while port 136 andchamber 19 are now connected by way of exhaust port 133 to thecontinuing negative pressure being induced through tube 132. Thus, thealternating vacuum or negative pressure conditions are induced onopposite sides of diaphragm 17 to produce its oscillating action.

The oscillating motion of diaphragm 17 produces the concomitantoscillating motions of pistons 66 and 91. Upon the downward motion ofpiston 66, atmospheric air which enters the piston housing throughapertures 104 pass through apertures 74 and apertures 72 into lowpressure piston chamber 67 above piston 66. Upon the up ward motion ofpiston 66, O-ring 49 seals off partition 28 while the air beingcompressed within chamber 67 passes through aperture 121 in pistonsection 36 into axial aperture 82 of piston section 81 and proceedsdownward past valve 84 into high pressure piston chamber 92 below piston91 which has moved into the upper position as shown in FIG. 1B.

Thereafter, when diaphragm 17 moves downwardly, pistons 66 and 91 alsomove downwardly during which time valve 84 becomes seated against valveseat 86 under the action of spring 87. The downward thrust of piston 91further compresses the air in piston chamber 92 to a pressure that ishigher than that which existed in piston chamber 67. The high pressureair from piston chamber 92 is urged by the action of the downwardmovement of piston 91 to open normally closed relief valve 112 againstthe action of spring 114 whereby the high pressure air is transmittedthrough outlet pipe 118 to work apparatus described hereinbefore.

In FIGS. 1A and 1B, the positions of pistons 66 and 91 are at rest atthe ends of their respective strokes and O-rings 69 and 94 are notperforming any sealing function in those positions.

In FIGS. 1C and 1E, said pistons have moved up wardly approximately 10%of their respective upstrokes from their positions shown in FIG. 1A. Byvirtue of increasing pressure in chamber 67 as a result of the upwardmovement of piston 66, O-ring 69 is urged downwardly against flange 73to provide a seal between piston 66 and the interior wall of chamber 67.At the same time, O-rings 69 and 94 are not performing any sealingfuncof the increasing pressure within chamber 67 to provide a sealbetween chamber 67 and vacuum chamber 19 where by all of the air beingcompressed in chamber 67 passes through aperture 121 in piston rodsection 36 and thence into axial aperture 82 of piston rod section 81thereby causing the opening of valve 84 against the action of spring 87whereby air under pressure is introduced into high pressure chamber 92.

As the compressed air enters into chamber 92 during the upward movementof piston 91, air pressure in chamber 92 urges O-ring 94 upwardlyagainst annular recess wall 98 (FIG. 1B) in order to seal off pistonchamber 92 from atmospheric air pressure that exists above piston 91.

Notwithstanding the friction effect between O-ring 94 moving upwardlyalong the inner surface of chamber 92, nevertheless the increasing airpressure within chamber 92 will cause said O-ring to be urged upwardlyagainst annular wall 98 of recess 93. Thus, the friction eflfect isoffset by the increasing pressure obtaining in chamber 92.

FIGS. 1D and IF represent the respective positions of pistons 66 and 91after about 10% of their down strokes from their respective locations inFIG. 1B. As piston 66 moves downwardly, O-ring 69 is urged upwardlyagainst flange 75 by friction with the interior wall of chamber 67whereby atmospheric air that has entered into chamber 67 through ports104 passes through ports 74 and ports 72 of piston 66 into the area ofchamber 67 above piston 66, said air bypassing O-ring 69 as it movesupwardly through ports 72. During the downward motion of pistons 66 and91, when negative pressure is being induced in chamber 19, said negativepressure is effective in urging O-ring 49 upwardly notwithstanding thedownward movement of piston rod 36, thereby providing an effective sealbetween vacuum chamber 19 and chamber 67 above piston 66. Accordingly,no vacuum leak occurs that would reduce the efiiciency of the negativepressure action taking place in chamber 19.

During the downward movement of piston 91 as shown in FIG. 1F, theincreasing pressure within chamber 92 below piston 91 causes O-ring 94to be urged upwardly against annular recess surface 98 to provide aneffective seal for the increasing pressure being induced in highpressure chamber 92.

Except for the time during the instantaneous reversal of motion ofdiaphragm 17 and of pistons 66 and 91, O-ring 49 performs its scalingfunction during both the upward and downward movements of piston rodsection 36. O-ring 49 is normally located within recess 47 with onlyslight peripheral squeeze being exerted against said O-ring when theapparatus is at rest. Said O-ring 49 is actuated to perform its sealingfunction during the downward motion of the pump components as shown inFIG. 1A by the induction of negative pressure within vacuum chamber 19in bell section 12 in order to seal off partition wall 28 and to preventany appreciable vacuum leak therethrough. The force of the negativepressure being induced in chamber 19 is greater than any frictionalforce that may be applied by the periphery of rod section 36 againstO-ring 49 that would otherwise move the latter away from its annularseat. During the upward movement of the pump components as shown in FIG.1B, the upward movement of piston 66 produces an increasing pressure inchamber 67 above said piston whereby said pressure causes O-ring 49 tobe urged upwardly against its annular seat to perform. its sealingfunction whereby the compressed air within chamber 67 above piston 66may be transmitted through axial aperture 82 into the high pressurecylinder chamber 92. Thus, O-ring 49 is caused to produce its scalingfunction between partition wall 28 and piston rod section 36 during bothrectilinear motions of said piston rod.

Notwithstanding the fact that control rod 23 extends from the interiorto the exterior of the apparatus housing through top wall 21 to performits function of operating the vacuum control mechanism, O-ring 26operates to preserve the integrity of the negative pressure beinginduced in vacuum chamber 18 without any appreciable vacuum leak as hasbeen experienced in prior art devices. While negative pressure is beinginduced in vacuum chamber 18 and rod 23 moves upwardly during at least aportion of that time, said negative pressure has sufficient force tourge O-ring 26 downwardly against its annular seat, overcoming anyupward frictional force being exerted by the periphery of said rodagainst said O-ring, thereby producing a vacuum seal between rod 23 andthe top wall 21 of bell section 11. During the downward movement of rod23 while negative pressure is being induced in vacuum chamber 19,chamber 18 is exposed during that time to atmospheric air whereby it isunnecessary to provide any seal between rod 23 and top wall 21 of bellsection 11. Also, the axial mounting of rod 23 obviates the necessitythat existed in prior art mounting of control elements that involved theprovision of bearings adjacent an aperture in a vacuum chamber wallthereby entailing considerable leakage of negative pressure both whenthe apparatus was performing its pumping function and when it was atrest.

, The per stroke capacity of the compound piston compressor of thepresent invention is determined by the capacity within low pressurechamber 67 whose volume is usually between about two to five times thatof high pressure chamber 92, or more. Substantially all of the air thatis within chamber 67 above piston 66 is pumped into the high pressurechamber 92, regardless of any and all trapped air therein, and said airis all pumped out from chamber 92 except for some residual high pressureair remaining in chamber 92 since piston 91 does not reach thebottom ofchamber 92 at the end of its downward stroke. The residual high pressureair remaining in chamber 92 below piston 91 at the end of its pressurestroke maintains O-ring 94 urged upwardly in a sealing position againstrecess wall 98 until pressure created by the upstroke of piston 66 andtransmitted into chamber 92 takes.

over and continues to maintain said O-ring in said sealing position.

According to performance tests of the compound piston compressordescribed herein, it has been found that the apparatus herein requiresappreciably less volume of negative pressure to oscillate diaphragm 17and appreciably fewer piston strokes to produce an amount of airpressure equal to that produced by other prior art compressors. Also,considerably less time is consumed in supplying or producing a givenamount of compressed air than other prior art types of compressors.

A salient feature of the invention is the novel arrangement for mountingcontrol rod 23 centrally and axially of diaphragm 17 and of pistons 66and 91, and of piston rod sections 36 and 81. By virtue of this axialmounting, the natural longitudinal reciprocating thrusts of all of themoving parts within the interior of bell sections 11 and 12, andcylinders 59 and 61, is preserved without distortion and withoutproducing any skewing action on said moving parts so that the latter canperform their pumping function with. high efliciency. This is incontrast to prior art devices where alternating vacuum controlmechanisms have been operated within the interior of the pump housingand located off center from the axis of the moving parts whereby pumpingefiiciency was diminished and alignment of the operating parts wasskewed and subjected to unbalanced stresses. According to the presentinvention, the location of the control rod in the axial positionproduces no unbalancing stresses upon the interior working parts of thepump. a

The balanced and undeviating axial reciprocating action of the operatingparts of the pump is preserved with the axial location of control rod 23whether the latter is operative through linkages to work alternatingvacuum control valves located olf center of the apparatus as shown inFIGS. 1-8, or when operating alternating vacuum control mechanismsmounted axially and aligned with said control rod on top of theapparatus as described in conjunction with FIGS. 9 and 10.

In prior art devices where actuating mechanisms were mounted otf centerupon pumping components in the interior pump housing, this produced offcenter stresses which resulted in the requirements of as much as twicethe power to operate alternating vacuum control mechanisms. Such wastein power is eliminated by the mounting of control rod 23 axially of theoperating parts in the present apparatus.

Although the present invention has been described with reference toparticular embodiments and examples, it will be apparent to thoseskilled in the art that variations and modifications can be substitutedtherefor without departing from the principles and true spirit of theinvention.

I claim:

1. A vacuum operated air compressor or pump comprising a housing, apumping assembly located in the interior of said housing, a vacuumoperated diaphragm connected to said pumping assembly in the interior ofsaid housing, a vacuum control valve located on the exterior of saidhousing for producing alternating movement of said diaphragm and amovable control member connected to said valve, said control memberextending through said housing and aligned axially in respect to saiddiaphragm and of saidpumping assembly and operated by said diaphragm toproduce alternating movements of said valve, said pumping assemblycomprising a low pressure piston and a high pressure piston mountedaxially in respect of each other, both of said pistons being located onone side only of said diaphragm in said housing, said low pressurepiston performing its pressure stroke only in one direction of movementof said diaphragm and said high pressure piston performing its pressurestroke only in the opposite direction of movement of said diaphragm.

2. Apparatus according to claim 1 wherein said pumping assembly islocated on one side only of said diaphragm and wherein said valve ismovable alternately into two oposite control positions, and furthercomprising a pair of biasing means operative in opposite directionsbetween said diaphragm and said control member for providing overthrustupon said control member to move said valve by snap action beyond thedead center position between its two opposite control positions.

3. Apparatus according to claim 2 wherein said pair of biasing means islocated in the interior of said housing.

4. Apparatus according to claim 2 wherein lost motion is providedbetween the action of said diaphragm and said control member in bothdirections prior to the interaction therebetween for producing therespective longitudinal motions of said control member.

5. Apparatus according to claim 1 and further comprising a seal memberbetween said control member and said housing, said seal member beingactivated by the induction of negative pressure in said housing adjacentsaid seal during the outward movement of said control member relative tosaid housing.

6. Apparatus according to claim 1 and further comprising a rodconnecting said diaphragm to said pumping assembly, an axial aperture insaid rod, a portion of said control member being movable longitudinallythrough 13 said aperture, spaced means in said rod within said aperturealternately engaging said control member in opposite directions ofmovement of said diaphragm to produce oscillating movements of saidcontrol member.

7. Apparatus according to claim 6 wherein lost motion relative to saidcontrol member is provided between the alternate engagements of saidspaced means with said control member.

8. Apparatus according to claim 6 and further comprising a springelement adjacent each of said spaced means, said spring elements beingoperative upon said control member in respective opposite directions toprovide overthrust for the movement of said control memher after thelatter is engaged by each of said spaced means.

9. A vacuum operated air compressor or pump comprising a housing, avacuum chamber in said housing, a vacuum operated diaphragm within saidvacuum chamber, a pumping chamber in said housing on one side only ofsaid vacuum chamber, a partition between said vacuum chamber and saidpumping chamber, and sealing means between said vacuum chamber and saidpumping chamber, a double-acting pumping assembly operating within saidpumping chamber, said pumping assem bly being connected to saiddiaphragm through said partition and said sealing means, saiddouble-acting pumping assembly performing a compression action duringboth opposite movements of said diaphragm.

10. Apparatus according to claim 9 wherein said double-acting pumpingassembly comprises first and second pistons aligned adjacently end toend and axially in respect of each other, a first piston chamber inwhich said first piston operates, a second piston chamber in which saidsecond piston operates, and means for transmitting air compressed bysaid first piston in said first chamber into said second chamber forfurther compression by said second piston.

11. Apparatus according to claim 10 wherein the capacity of said firstchamber is in the range of about two to ten times the capacity of saidsecond chamber.

12. Apparatus according to claim 9 wherein said sealing means isactuated during the movement of said diaphragm and of said pumpingassembly in one direction by the negative pressure being induced in saidvacuum chamber on one side of said partition and is actuated during themovement of said diaphragm and of said pumping assembly in the oppositedirection by the positive pressure produced by said pumping assembly asit moves toward said partition.

13. Apparatus according to claim 12 wherein said sealing means comprisesan O-ring in said partition, said O- ring performing its sealingfunction in one direction only during both movements in oppositedirections of said diaphragm and of said pumping assembly in unison.

14. Apparatus according to claim 13 and further comprising a rodconnected between said diaphragm and said pumping assembly, said rodmoving through said partition and within said O-ring, said O-ringforming an elfective seal between said rod and said partition during therectilinear movements of said rod.

15. A vacuum operated air compressor or pump comprising a housing, avacuum chamber in said housing, a vacuum operated diaphragm within saidvacuum chamber, a pumping chamber in said housing on one side only ofsaid vacuum chamber, a partition between said vacuum chamber and saidpumping chamber, a double-acting pumping assembly operating within saidpumping chamber, said pumping assembly being connected to said diaphragmthrough said partition, means for maintaining a seal in said partitionbetween said vacuum chamber and said pumping chamber, a vacuum controlvalve located on the exterior of said housing for producing alternatingmovement of said diaphragm and a control member connected to said valve,said control member extending through the opposite side of said housingand arrayed axially in respect of said diaphragm and of said pumpingassembly, said control member, said diaphragm and said pumping assemblymoving longitudinally and reciprocably in the same direction, saidcontrol member being operated by said diaphragm to produce alternatingmovements of said valve, said double-acting pumping assembly performinga compression action during both opposite movements thereof.

16. Apparatus according to claim 15 wherein said valve is movablealternately into two opposite control positions, and further comprisinga pair of biasing means operative in opposite directions between saiddiaphragm and said control member for providing overthrust upon saidcontrol member to move said valve by snap action beyond the dead centerposition between its two opposite control positions.

17. Apparatus according to claim 16 wherein said pair of biasing meansis located in the interior of said housing.

18. Apparatus according to claim 16 wherein lost motion is providedbetween the action of said diaphragm and said control member in bothdirections prior to the interaction therebetween for producing therespective longitudinal motions of said control member.

19. Apparatus according to claim 15 and further comprising a sealbetween said control member and said housing, said seal being activatedby the induction of negative pressure in said housing adjacent said sealduring the out ward movement of said control member relative to saidhousing.

20. Apparatus according to claim 15 wherein said seal is actuated duringthe movement of said diaphragm and of said pumping assembly in onedirection by the negative pressure being induced in said vacuum chamberon one side of said partition and is actuated during the movement ofsaid diaphragm and of said pumping assembly in the opposite direction bythe positive pressure produced by said pumping assembly as it movestoward said partition.

21. Apparatus according to claim 20 wherein said sealing means comprisesan O-ring in said partition, said O-ring performing its sealing functionin one direction during the movement in both oppositedirections of saiddiaphragm and of said pumping assembly.

22. Apparatus according to claim 21 and further comprising a rodconnected between said diaphragm and said pumping assembly, said rodmoving through said partition and within said O-ring, said O-ringforming an effective seal between said rod and said partition during therectilinear movements of said rod.

23. A pump comprising a housing, a bell section in said housing, aflexible diaphragm in said bell section dividing said section into twovacuum chambers, means for alternately inducing negative pressuresuccessively in said vacuum chambers to cause said diaphragm tooscillate within said bell section, a first low pressure cylinder insaid housing, a second high pressure cylinder in said housing, saidfirst and second cylinders being aligned longitudinally in respect ofeach other on one side only of said bell section, sealing meansisolating said bell section from said cylinders, a first low pressurepiston movable longitudinally within said first cylinder, a second highpressure piston movable longitudinally within said second cylinder, apiston rod connected to said diaphragm, said first and second pistonsbeing mounted on said rod whereby said diaphragm and said two pistonsmove reciprocably longitudinally in unison, said first piston producinga compression stroke in one direction only, said second piston producinga compression stroke in the opposite direction only, and means fortransmitting air compressed by said first piston in said first cylinderinto said second cylinder.

24. A pump according to claim 23 and further com prising valve meanslocated externally on said housing for alternately inducing negativepressure in said two vacuum chambers, an axial aperture in said pistonrod,

a control element extending through said bell section and movablelongitudinally within said axial aperture, said control element beingconnected to said valve means, means on said control element within saidaxial aperture and means in said piston rod within said axial aperturecooperating to produce oscillating movements on the part of said controlelement which, in turn, produces reversing movements on the part of saidvalve means for alternating the pressure conditions in the respectivevacuum chambers.

25. A pump comprising a housing, a bell section in 'said housing, aflexible diaphragm mounted in said bell section and dividing theinterior thereof into first and second vacuum chambers, means forsubjecting said first and second vacuum chambers alternately to negativepressure and to atmospheric pressure for moving said diaphragmreciprocably within said bell section, a first and second cylinders,sealing means mounted between I said rod and said partition isolatingsaid bell section from said first cylinder, said sealing means beingactivated in one direction of the rod movement by pressure produced insaid first cylinder and being activated in the reversev direction of therod movement by negative pressure being induced in the first vacuumchamber adjacent said partition.

26. A pump according to claim and further comprising a first pistonmounted on said piston rod and operative within said first cylinder, asecond pistpn mounted on said piston rod and operative within saidsecond cylinder, and means in said piston rod for transmitting aircompressed by said first piston within said first cylinder into saidsecond cylinder.

27. A- pump according to claim 26 wherein said first cylinder has alarger diameter than said second cylinder.

28. A pump according to claim 25 and further comprising valve meanslocated externally on said housing for alternately inducing negativepressure in said two vacuum chambers, a control element within said bellsection and extending externally thereof, the external portion of saidcontrol element being connected to said valve means, said controlelement being operated by said diaphragm to produce oscillatingmovements on the part of said valve means for alternating the pressureconditions in said respective vacuum chambers.

32. A pump comprising a housing, a bell section in said housing, aflexible diaphragm mounted in said bell section and dividing theinterior thereof into first and second vacuum chambers, means forsubjecting said first and second vacuum-chambers alternately to negativepressure and to atmospheric pressure for moving said diaphragmreciprocably within said bell section, a first low pressure cylinder insaid housing, a second high pressure cylinder in said housing, saidfirst and second cylinders 'being aligned longitudinally in respect ofeach other on one side only of said bell section, said low pressurecylinder having .a greater diameter than said high pressure cylinder, apartition between said low pressure cylinder and said first vacuumchamber, a piston rod connected to said diaphragm, an aperture in saidpartition through which said rod moves reciprocably, said rod extendinginto said low pressure cylinder and said high pressure cylinder, a lowpressure piston mounted on said rod and moving reciprocably within saidlow pressure cylinder, a high pressure piston mounted on said rod andmovable reciprocably within said high pressure cylinder, sealing meansmounted between said rod and said partition effectively isolating saidfirst vacuum chamber from said low pressure cylinder, said sealing meansbeing acti vated by pressure produced by the compression stroke of saidlow pressure piston, said sealing means being activated during thereverse stroke of said low pressure piston by negative pressure beinginduced in said first vacuum chamber, and means for transmitting aircompressed within said low pressure piston into said high pressurecylinder.

29. A pump according to claim 28 and further comprising an axialaperture in said piston rod, a portion of said control element withinsaid bell section extending into said aperture and movable freelylongitudinally therein, means on said control element and means withinsaid aperture cooperating only near the respective ends of thereciprocating motions of said diaphragm to cause said control element tooperate said valve means.

30. A pump according to claim 29 and further comprising a first biasingelement at the top ofsaid aperture and a second biasing element at thebottom of said aperture, said first and second biasing elementscooperating with said control element to provide an overthrust for saidcontrol element during an intermediate portion of its movements inopposite directions.

31. A pump-according to claim 28 and further comprising a sealingelement between said control element and said bell section, said sealingelement effectively preserving the negative pressure being induced insaid second vacuum chamber.

33. A vacuum operated air compressor or pump comprising a housing, avacuum chamber in said housing, a vacuum operated diaphragm mounted forreciprocating action within said vacuum chamber, a pumping chamber insaid housing on one side only of said vacuum chamber, a sealed partitionbetween said vacuum chamber and said pumping chamber, a double-actingpumping assembly in said pumping chamber and connected to said diaphragmthrough said partition, said pumping assembly moving reciprocably withinsaid pumping chamber whereby the movement of said assembly in eachopposite direction thereof constitutes a half cycle of operation of saidpump, said pumping assembly performing a compression action during eachhalf cycle of reciprocating movement thereof.

34. Apparatus according to claim 33 wherein said pumping assemblycomprises first and second axially aligned adjacent pistons, a firstcylinder within which said first piston operates, a second cylinderwithin which said second piston operates, the air compressed by thepressure stroke of said first piston during one half cycle of pumpoperation being urged into said second cylinder where it is furthercompressed by the pressure stroke of said second piston during theother, half cycle of pump operation.

References Cited UNITED STATES PATENTS 862,867 8/1907 Eggleston 103-152XR 1,825,411 9/1931 Murphy 103 50 XR 2,235,544 3/1941 Wold 103-502,856,116 10/1958 Hogan 230-52 2,943,765 7/1960 Glasgow et al. 103-50 XR3,339,830 9/1967 Graham 230-52 ROBERT M. WALKER, Primary Examiner US.01. X.R.

